Bottom dump door actuating mechanism for vehicles



Dec. 3, 1968 R. H. KRESS ETAL 3,413,894

BOTTOM DUMP DOOR ACTUATING MECHANISM FOR VEHICLES Original F iled Oct. 23, 1965 5 Sheets-Sheet l N f H 2 m O\ m\ x I r R INVENTORS RALPH H. KRESJS JACKSON C.. MEDLEY BY DONALD E. MERRITT ATTORNEYS Dec. 3, 1968 I R. H. 'KRESS ETAL 3,413,894

BOTTOM DUMP DOOR ACTUATING MECHANISM FOR VEHICLES Original Filed Oct. 23, 1965 5 Sheets-Sheet 2 Fig-E- INVENTORS RALPH H. KRESS JACKSON C. MEDLEY v BY DONALD E. MERRH'T ATTORNEYS BOTTOM DUMP DOOR ACTUATING MECHANISM FOR VEHICLES Original Filed Oct. 23, 1965 5 Sheets-Sheet 5 INVENTORS RALPH H. KRES JACKSON c. ME EY DONALD E. MERRITT ATTORNEYS United States Patent 3,413,894 BOTTOM DUMP DOOR ACTUATING MECHANISM FOR VEHICLES Ralph H. Kre'ss, Peoria, Jackson C. Medley, East Peoria, and Donald E. Merritt, Peoria Heights, Ill., assignors to Caterpillar Tractor (30., Peoria, Ill., a corporation of California Original application Oct. 23, 1965, Ser. No. 503,037,- now Patent No. 3,356,416, dated Dec. 5, 1967. Divided and this application Apr. 3, 1967, Ser. No. 649,379

2 Claims. (Cl. 91-28) ABSTRACT OF THE DISCLOSURE A hydraulic jack including a cylinder having large and small diameter sections and a piston having corresponding large and small diameter sections located in the cylinder. The cylinder has a discharge opening in its "large diameter section adjacent the small diameter section; and the piston has a check valve in both its large and small diameter sections to eifect either partial or full extension of the jack.

Cross-reference to related applications This is a division of application Ser. No. 503,037, filed Oct. 23, 1965, now U.S. Patent 3,356,416, issued Dec. 5, 1967.

Background of the invention This invention relates to power actuated mechanism for opening and closing the doors on bottom dump trucks or the like.

The invention is designed particularly for very large material hauling vehicles such as the 240 ton capacity vehicle disclosed in our assignees co-pending application of Ralph H. Kress and Jackson C. Medley entitled Suspension System for Heavy Vehicles, filed Sept. 21, 1965, Ser. No. 488,985, now U.S. Patent 3,330,578, issued July 11, 1967.

Vehicles of the kind disclosed herein are often used in mining operations and their contents dumped through bottom opening doors into bins or the like where it isdesired that the doors be only partially opened to avoid spilling the material on the sides of the bins and in the path of travel of the vehicle wheels. It is also desirable sometimes to dump material in windrows and in this case the doors should be fully open.

It is an object of the invention to provide actuating mechanism to open and close bottom dump doors in Which the doors may be selectively partially or fully opened. It is a further object of the invention to provide hydraulic actuating means for doors of the kind described comprising a hydraulic motor and means to prevent the weight of the doors when they are closed and the weight of the load on the doors from being transmitted to the hydraulic motors.

It is a still further object of the present invention to pro vide a special hydraulic jack which is operable, selectively through a short stroke or a long stroke for causing partial and full opening of doors or the like.

Still further objects and advantages of the invention are made apparent in the following specification wherein reference is made to the accompanying drawings for a detailed disclosure.

In the drawings:

FIG. 1 is a view in side elevation of a large truck embodyin g the present invention;

FIG. 2 is a sectional view with parts broken away and taken on the line II-II of FIG. 1; and

FIG. 3 is a central longitudinal section view through a hydraulic jack used for actuating the bottom dump doors to which the invention pertains.

3,413,894 Patented Dec. 3, 1968 ICC The truck shown in FIG. 1 has a large body 10 for carrying material which may be discharged from bottom dump doors to be described. Two large tractor units 12 and 14 support the body 10 through king pins 15 and 16. Each tractor unit has its own operators cab 17 and 18 equipped with dual controls so that all operations can be controlled from either cab. A partition shown in dotted lines at 20 extends transversely of the truck body midway between its ends for strengthening the body and to provide a space for door actuating mechanism where it is protected from damage by contact with materials being hauled.

The arrangement of door actuating mechanism within the space provided by the partition 20 is shown in FIG. 2 wherein the near wall of the partition is partially broken away. In this figure, bottom dump doors are shown at 22 as pivotally suspended from pivots 23 arranged at opposite ends of the body. This enables the doors to be swung through the broken line positions illustrated in connection with the door at the left side of the body, the position 22a being a partially open position and the position 22b being a fully opened position in which the further opening movement is limited by engagement of pads 25 on the doors and stops 26 on the body. The mechanism for opening and closing one door is illustrated, it being understood that the mechanism for the other door is identical.

A supporting bracket of U-shaped cross-section illustrated at 27 is provided on each side of a central partition 28 which divides the partition 20 into two compartments. Each bracket provides a pivot 29 for a bell crank lever 30 which is actuated by a hydraulic jack 31 disclosed in greater detail in FIG. 3. The jack cylinder is pivoted as at 32 in the bracket 27 and the rod is piivotally connected at 33 to one end of the lever 30. The full line position of the lever 30 is the position occupied with the door 22 closed and the upper end of the lever contacts an adjustable stop 34. A rod 35 is pivotally connected with a bracket 36 on the door and at its opposite end to the lever 30. In the closed position shown the upper connection of the rod 35 is over center with respect to the pivotal support of the lever so that weight of the door or any portion of the load resting on the door willl tend to close the door rather than to open it and will therefore not be imposed on the hydraulic cylinder and other components of the hydraulic circuit.

Hydraulic jack 31 may be partially extended to swing the door to the position shown at 2211 or may be fully extended to swing the door into the position illustrated at 22b. This is accomplished through structure shown in FIG. 3 wherein the jack is shown as having a rod 38 with a piston head 39 at one end thereof and a smaller or auxiliary head 40 associated therewith. The hydraulic circuitry and controls are not disclosed herein as they are not considered necessary to an understanding of the present invention. It will suflice to know, however, that the door jacks may be actuated from controls in either tractor cab and that they may be supplied selectively with hydraulic fluid at a nominal pressure of say 1,000 pounds or a higher pressure of 1,600 to 2,000 pounds. The jack of FIG. 3 is illustrated in its retracted position as with the doors closed. To open the doors to a partially open position, fluid is supplied at the lower pressure at the head end of the jack as through a passage 42. Fluid from the rod end of the jack is discharged and returned to the source through passage 44. When the auxiliary head 40 of the piston enters a reduced diameter in the cylinder 31 provided by a sleeve 46 exit of fluid through passage 44 is prohibited and the piston comes to rest against the body of fluid within the sleeve. This is the partially extended position which movps the door to the position shown at 22a in FIG. 2.

To impart further or full opening to the door the higher pressure is directed to the cylinder through the port 42 and so increases the pressure within the sleeve 46 until it opens a spring-closed check valve shown at 48 permitting fluid to escape from the sleeve through the auxiliary piston 40 and out through the passage 44. Closing of the doors is effected by directing pressure inwardly of the cylinder through passage 44 which will first be effective against a surface 50 in back of the piston 39 and later also against the face of the auxiliary piston 40.

During opening of the doors, the great weight of the load within the body tends to open the doors more rapidly than fluid can be expelled from the rod end of the jack through the passage 44. In order to prevent undesirable delay in the opening of the doors excessive pressure in the rod end of the jack is relieved through a spring-closed check valve 52 communicating pressure from the rod end through the piston to the opposite end of the jack or in effect bypassing fluid to permit increased speed of the door opening operation.

We claim:

1. A hydraulic jack for opening a door to either of two positions comprising a cylinder with an area of small diameter adjacent one end and an area of larger diameter toward the opposite end, an extensible rod having a piston with a portion fitting said small diameter and a portion fitting the larger diameter, a discharge passage in the large diameter part of the cylinder adjacent the small diameter part whereby fluid in the small diameter part will prevent extension and prevent discharge of fluid through the passage when the piston enters the small diameter part, and check valve means opening communication between the small diameter part of the cylinder and the discharge passage when the small diameter portion of the piston is in the small diameter portion of the cylinder and when a predetermined pressure is attained.

2. The combination of claim 1 with a second check valve means in the piston for admitting fluid from the discharge portion of the cylinder to a supply side of the cylinder when pressure in the discharge portion exceeds a predetermined value.

References Cited UNITED STATES PATENTS 2,408,338 9/1946 Parsons 91-392 2,558,810 7/1951 Bent 91-392 2,786,452 3/1957 Tucker 91395 2,807,081 9/1957 Black 91-399 2,986,123 5/1961 Augustin 91-422 3,106,870 10/1963 Abrams 91-395 3,259,026 7/1966 Madland 91436 CARROLL B. DORITY, JR., Primary Examiner. 

